parameters, return, math, graphics nobody expects the spanish inquisition!

parameters parameters are declared by writing their names no types needed! def name(parameter, parameter,..., parameter): statements

parameters >>> def print_many(word, n):... for i in range(n):... print word >>> print_many("spam", 4) spam

exercise rewrite Stars2.java in python ****************************************************************** ***************** ** ******

stars2.py 1 # Draws a box of stars with the given width and height. 2 def box(width, height): 3 print width * "*" 4 for i in range(height - 2): 5 print "*" + (width - 2) * " " + "*" 6 print width * "*" 7 8 # main 9 print 13 * "*" 10 print 7 * "*" 11 print 35 * "*" 12 box(10, 3) 13 box(5, 4)

default parameter values can make parameter(s) optional by specifying a default value >>> def print_many(word, n=1):... for i in range(n):... print word >>> print_many("shrubbery") shrubbery >>> print_many("shrubbery", 4) shrubbery

parameter keywords can pass parameters in any order by specifying their names when calling >>> def print_many(word, n):... for i in range(n):... print word >>> print_many(n=3, word="Ni!") Ni!

math from math import *

Function nameDescription ceil(value)rounds up cos(value)cosine, in radians degrees(value)convert radians to degrees floor(value)rounds down log(value, base)logarithm in any base log10(value)logarithm, base 10 max(value1, value2,...)largest of two (or more) values min(value1, value2,...)smallest of two (or more) values radians(value)convert degrees to radians round(value)nearest whole number sin(value)sine, in radians sqrt(value)square root tan(value)tangent ConstantDescription e pi more:

returning values just like in Java! def name(parameters): statements return value

returning values >>> def ftoc(temp):... tempc = 5.0 / 9.0 * (temp - 32)... return tempc >>> ftoc(98.6) 37.0

drawingpanel put drawingpanel.py in the same folder as your program from drawingpanel import * panel’s canvas field behaves like Graphics g need to put panel.mainloop() at the end of your program

draw.py 1 from drawingpanel import * 2 3 panel = DrawingPanel(400, 300) 4 panel.set_background("yellow") 5 panel.canvas.create_rectangle(100, 50, 200, 300) 6 panel.mainloop()

drawing methods notice methods take x2 / y2 parameters, instead of width/height JavaPython drawLinepanel.canvas.create_line(x1, y1, x2, y2) drawRect, fillRect panel.canvas.create_rectangle(x1, y1, x2, y2) drawOval, fillOval panel.canvas.create_oval(x1, y1, x2, y2) drawStringpanel.canvas.create_text(x, y, text="text") setColor(see next slide) setBackgroundpanel.set_background(color)

colors no fillRect, fillOval, or setColor instead, pass outline and fill parameters when drawing a shape list of all colors: s.png s.png

drawcolors.py 1 from drawingpanel import * 2 3 panel = DrawingPanel(400, 300) 4 panel.canvas.create_rectangle(100, 50, 200, 200, outline="red", fill="yellow") 5 panel.canvas.create_oval(20, 10, 180, 70, fill="blue") 6 panel.mainloop()

polygons draw polygons with create_polygon draw line groups by passing more parameters to create_line 1 from drawingpanel import * 2 3 panel = DrawingPanel(200, 200) 4 panel.canvas.create_polygon(100, 50, 150, 0, 150, 100, fill="green") 5 panel.canvas.create_line(10, 120, 20, 160, 30, 120, 40, 175) 6 panel.mainloop()

exercise draw a car!

car.py 1 from drawingpanel import * 2 3 panel = DrawingPanel(200, 100) 4 panel.set_background("gray") 5 6 panel.canvas.create_rectangle(x, y, x+100, y+50, fill="black") 7 panel.canvas.create_oval(x+10, y+40, x+30, y+60, fill="red", outline="red") 8 panel.canvas.create_oval(x+70, y+40, x+90, y+60, fill="red", outline="red") 9 panel.canvas.create_rectangle(x+70, y+10, x+100, y+30, fill="cyan", outline="cyan") panel.mainloop()

exercise parameterize it!

car2.py 1 from drawingpanel import * 2 3 def car(panel, x, y): 4 panel.canvas.create_rectangle(x, y, x+100, y+50, fill="black") 5 panel.canvas.create_oval(x+10, y+40, x+30, y+60, fill="red", outline="red") 6 panel.canvas.create_oval(x+70, y+40, x+90, y+60, fill="red", outline="red") 7 panel.canvas.create_rectangle(x+70, y+10, x+100, y+30, fill="cyan", outline="cyan") 8 9 panel = DrawingPanel(300, 200) 10 panel.set_background("gray") car(panel, 10, 30) 13 car(panel, 170, 80) 14 car(panel, 50, 120) panel.mainloop()

exercise animate it using panel.sleep() !

car3.py 1 from drawingpanel import * 2 3 def car(panel, x, y): 4 panel.canvas.create_rectangle(x, y, x+100, y+50, fill="black") 5 panel.canvas.create_oval(x+10, y+40, x+30, y+60, fill="red", outline="red") 6 panel.canvas.create_oval(x+70, y+40, x+90, y+60, fill="red", outline="red") 7 panel.canvas.create_rectangle(x+70, y+10, x+100, y+30, fill="cyan", outline="cyan") 8 9 panel = DrawingPanel(500, 100) for x in range(0, 400, 10): 12 panel.canvas.create_rectangle(0, 0, 500, 100, fill="gray", outline="gray") 13 car(panel, x, 10) 14 panel.sleep(10) panel.mainloop()